Preparation of laminate metal stock by use of organic anti-welding materials



Oct. 26, 1965 BRlCK ETAL 3,214,251

PREPARATION OF LAMINATE METAL STOCK BY USE OF ORGANIC ANTI-WELDINGMATERIALS Filed July 20, 1960 T1111 TUE-.2

so I Ila-.5 32 33 f f l E:]--- Hammagg hummus-K. 5351 INVENTORS 205521M. 22mm, zaaaz-r B. MEslzoamu BY (5* Au'rs HAnssou ATTOIZN EYS UnitedStates Patent PREPARATION OF LAMINATE METAL STOCK BY USE OF ORGANIC ANTIWELDING MATERIALS Robert M. Brick and Robert B. Mesrobian, Hinsdale, andAnts Hansson, Evanston, Ill., assignors to Continental Can Company,Inc., New York, N.Y., a corporation of New York Filed July 20, 1960,Ser. No. 44,148 28 Claims. (Cl. 29-183) This invention relates to theemployment of organic materials for preventing the welding of metal inthe making of laminate stock.

It is known to provide a metal billet with an internal discontinuitycontaining an anti-welding or resist material, and to roll the same forproducing a laminate stock. Prior practices have been to employrefractory solid powders such as alumina, silica, graphite, mica, talc,gypsum and the like, for the reason that the rolling is most,efficaciously effected by a schedule of heat treatments, with successivehot and cold rolling. The billet could be an ingot having one or morelongitudinal channels filled by such a resist, and produced by castingthe metal around a coherent core of such resist material; orlongitudinal hollow channels could be formed during casting, orsubsequently by drilling, and later filled with the resist material. Thebillet may be originally 8, 12 or more inches in thickness, and theinternal discontinuity may be /2 inch or more thick; noting that whenthe refractory resist powder is later introduced, the permissibleminimum thickness depends upon the ability to produce an essentiallyuniform deposit of the powder therein: and that when a preformed core ofcoherent refractory powder is used, a similar minimum must be observedto avoid disruption during the casting. The purpose of the resist orantiwelding compound is to prevent the welding or sticking together ofthe laminations, and for this a microscopically thin film is aseffective as a thicker one: noting that the metal provides thelaminations which produce the final product. It is desirtble to keep theresist dimension as thin as possible in the ingot but thicknesses ofless than a half-inch, in an ingot which is 6 to 14 feet long, are noteasily filled to uniform packing density with a dry refractory powder.

When a refractory powder is employed as the resist, and the rollingoperation produces a relative displacement of the powder along theinternal discontinuity during the rolling, a part of the powder isusually expelled at the trailing end as this passes through the rolls.Refractory powders such as aluminum oxide are frequently employed, whichare recognized abrasive agents: and the expelled powders can damage therolls and their bearings.

Most organic materials undergo extensive thermal decomposition uponheating in air at temperatures around 500 degrees F. Such decompositionmay be by any of a group of complex reaction including depolymerizationor disproportionation; and particularly may be catalyzed by contact withmetal. In general, it has been expected in the art of coating withorganic enamels or lacquers that breakdowns will occur at temperaturesof 600 degrees F. or below even with very short exposure time. On theother hand, normal heat treatment and hot rolling schedules foraluminum, copper, zinc, magnesium and other non-ferrous metals and theiralloys call for heating to a temperature of around 445 to 540 degrees C.(700 to 1,000 degrees F.) for periods of ten minutes up to four or morehours.

It has now been found that liquefiable materials as set out hereinaftermay be introduced into billet channels, with the billet being heated andthen subjected to a schedule of hot and cold rolling, without loss ofthe ability of the organic compound to function as an antiweldingmaterial during the hot and cold rolling operations by which a billet 12inches thick may be reduced to a total thickness of, say, 0.016 inchwith two metal laminations each 0.008 inch thick being separated by amicroscopically thin residual layer of the resist material. The functionof preventing welding is then not dependent upon the particle size ofthe resist residue, and therewith the original channel in the billet,for receiving the resist, may be made much thinner than with powderresists, e.g., organic resists in channel A; inch or less thick arefound as effective in an ingot as a powder resist thickness of /z inchor more, and therewith calipering of the final thickness of the rolledlaminate strip can directly determine the thickness of each laminationwithout need of allowance for the resist residue.

Hot rolling, as applied to the metal, herein refers to a temperaturecondition at which the metal does not exhibit strain-hardening: andcold-rolling of the metal to a temperature at which strain-hardeningoccurs. For example, hot-rolling of aluminum alloys ceases as thematerial cools to about 650 degrees F., and the subsequent rolling atlower temperatures effects strain-hardening.

Further, organic compounds can be chosen, in accordance with thisinvention, which do not require removal, but which bond directly withlater-applied organic enamels and lacquers and in effect become a partthereof.

The word liquid is herein used to define that state of the selectedanti-welding substance in which the molecules are able to change theirpositions plastically with respect to one another at the temperature andunder the local pressure effects of hot-reduction of the metal whichsurrounds and encloses the substance and in which the said substancespreads to occupy the cross-section of the channel during thehot-reduction: with the relative movement being restricted byinter-molecular forces so that an essentially fixed volume ismaintained. Therewith the substance does not fracture under the heat andpressure of hot reduction, but retains continuity and in part movesalong the channel as the metal and the anti-welding substance are beingreduced in thickness and extended in length. The word solid is hereinused to define that state at a lower temperature of an organic compound,which is liquid at a higher temperature, at which the molecules are sostrongly coupled that the compound does not flow under the action ofgravity, and in which it exerts a stiff resistance to molecular changeof relative position but has capability of being extended and ofmaintaining a continuous layer between the surfaces of the channelduring cold-reduction, without exhibiting brittleness or breaking intofragments which separate from one another during the course of the coldreduction and permit the movement of the metal forming such surfacesinto welding contact with one another. The words melting andliquefaction are used herein to define the change of such anti-weldingsubstances, upon heating to the hot reduction or treating temperature,so that its viscosity is lowered and its ability to flow is increasedwhereby it spreads and produces within the billet being rolled acontinuous body of weld-preventing material.

An object of this invention is the reparation of a metal billetcontaining a longitudinal internal channel, and the heating and rollingof the same for producing a laminate strip, with the employment in the:channel of an anti-welding or resist material which is stiffly resistantto flow at room temperature, which becomes liquid at the temperature andpressure scheduled for the hot-rolling of the billet, and which is latereffective during cold-rolling to undergo deformation and extension orfor maintaining its anti-welding action.

Another object of this invention is the preparation of a metal billetcontaining an organic resist, and the reduction of the same to a desiredover-all thickness by a schedule including hot-rolling and heattreatment at temperatures appropriate to the metal.

Another object is the employment, as a resist, of a material ofnon-abrasive characteristics, and therewith having essentially noabrasive action upon the rolls, tools, and other equipment coming incontact therewith.

Another object is the employment, as a resist, of an organic compoundcompatible with an organic enamel or lacquer later applied thereover.

A further object is the employment, as a resist, of an organic compoundwhich, during the course of a schedule of hot and cold rollings, remainseffective to prevent welding of metal laminae separated thereby, and tomaintain such behavior in extremely thin layers and therewith providesmooth adjacent surfaces on such laminae.

A further object is the preparation of laminate stock by forming aningot with a small internal channel, filling the channel with a resistwhich is liquid at the beginning of hot-rolling, and final rolling ofthe same with passes which are at temperatures under which the resist isessentially an extensible solid.

With these and other objects and features in view, as will appear in thecourse of the following description and claims, illustrative embodimentsof the invention are set out in conjunction with the accompanyingdrawings, in which:

FIGURE 1 is a perspective view of part of a billet having core channelsor internal discontinuities with parallel plane sides and chisel-shapededges;

FIGURE 2 is a perspective view of a part of a billet having corechannels of rounded edge form;

FIGURE 3 is a perspective view, showing the ingot end being closed bypeening and welding;

FIGURE 4 is a perspective view of an ingot having longitudinal internalchannels, being filled with an organic resist;

FIGURE 5 shows in conventionalized block form a schedule of heating androlling operations;

FIGURE 6 is a conventionalized perspective view showing the placing of aresist in a billet channel immediately prior to hot rolling;

FIGURE 7 shows, on a larger scale than FIGURES 1 to 6, a part of amulti-wide rolled strip;

FIGURE 8 shows the opening or expansion of a section of the strip toform a tubular body;

FIGURE 9 shows the application of an organic enamel to the interiorsurface of such a body.

It has been found that many high molecular organic compounds can beemployed as anti-welding or resist materials in hot working billets intolaminate stock, e.g., with a schedule of beatings and hot rollings, whenthey are protected from oxygen during the operations. Such can beaccomplished by heating the billet to hot-rolling temperature,introducing the resist into the internal channel or channels, thenperforming a first rolling step for distributing the resist and reducingthe channel sections so that the same are filled with resist essentiallyfrom end to end of the billet, whereby the billet itself prevents accessof air to the resist except at the end openings of the channels, andcontinuing the hot rolling prior to the cooling of the billet and withina time period of a few minutes: noting that many of the compoundsdegrade at a timeztemperature function which enables them to remaineffective as resists for times up to an hour or more and that all namedcompounds remain effective for at least five minutes at the hot-rollingtemperatures provided that the air exposure prior to completion of thefirst pass is restricted. Alternatively, the protection from oxygen canbe accomplished by placing the resist in such discontinuities andsealing the openings as by welding, before subjection to the highheating of the specified schedule. The resist may be inserted into thecold billet block, the

lblock welded, and the scheduled beatings and workings performed; or theblock may be heated to a temperature effective for liquefying the resistwithout its degeneration in the presence of air, filled and then weldedshut, and the scheduled beatings and workings performed. In cases wherethe resist is charged into a cold billet, or into a billet heated to thetemperature for liquefaction but not a quick degradation of the resistwhen heated in contact with air, a preliminary breakdown or conformancerolling may be accomplished to distribute the resist and reduce thechannel section so that it is filled by the resist with expulsion ofair, before the billet is heated to the temperature for the start of thehot rolling. The choice of specific procedure depends upon equipmentavailable and economics, and upon the physical form of the resist atroom temperature. For example, when the resist is in powdery form, themelting and the escape of air from the pores may cause bubbling withpassage of some of the liquid material into regions where closurewelding is to be done: and in such cases, a low temperature heating forliquefaction is preferred, followed by the expulsion of air before theclosure and heating to hot rolling temperatures. On the other hand, ifthe available equipment permits the homogenizing heating of the emptybillet, followed by a quick introduction of the resist, no sealing ofthe charged end of the channel is necessary, if this charging. isquickly followed by the initiation and completion of the hot rolling.

It has been found that organic resists which appear harder than thebillet metal can be employed, in cold rolling, provided that the film isthin relative to the thick- :ness of the metal laminations during therolling pass.

For example, an epoxide resin (e.g., that sold commercially under thename Epon-1007), which appeared harder than aluminum, could be employedsuccessfully by heating the billet and hot rolling until the epoxy resinresist film had a thickness of a few thousandths of an inch, duringwhich the resist spread easily as a film: thereafter, a cold rollingproceeded with extension of the film by rupture into flakes whichflattened and spread and prevented cold welding.

In general, these organic resists work both when the rolling is hot withlittle work-hardening of the metal; and later when the rolling is coldwith a relatively high workhardening of the metal.

A characteristic observed is that, because many of the resist materialsappear to have greater adhesion to the metal than cohesion, the finalstrip produced permits the opening or expansion with both internal metalsurfaces having parts of the residual resist layer clinging to them.

Examples of practice in which the empty billet is heated to hot rollingtemperature, charged with resist, and quickly rolled, are:

Example I An aluminum billet having a longitudinal internal channel waswelded closed at one end. The billet was heated to 900 degrees F.; theopen end raised, and a solid epoxide resin introduced as a resist intothe chanel until the channel was substantially full. The resin melted asit entered and flowed downward to form the fill. The epoxide resin was abis-phenol epichlorohydrin condensate, and is illustrative of the epoxyresins which can be empolyed, being a solid at room temperature andbecoming liquid at 300 degrees F., being obtainable as flakes or pelletswhich may be converted to a power: the resin commercially avilable underthe trademark Epon- 1007 was satisfactory. The billet was immediatelyhotrolled, with the open or charging end first presented to the rolls;and then cold-rolled, preferably after an anneal reheating to 900degrees F., and a cooling before the coldrolling. An original billet of2 to 12 inch thickness can be hot-rolled to, say, 0.120 inch thickness,and then reduced to 0.016 inch by cold-rolling, to provide a laminatestrip having two metal laminations connected integrally Example 2 A redbrass billet (85 percent copper, 15 percent zinc) having an internallongitudinal channel with a metal wall thickness of Ms inch was heatedto 950 degrees F., a slab or strip of the epoxide resin of Example 1 wasintroduced, and the hot rolling immediately started, bringing the billetto 0.060 inch gauge. The strip was anealed at 1,100 degrees F., cooledand cold-rolled to a final gauge of 0.016 inch. The metal laminationscould readily be separated and bent apart to form a tubular body.Although there was no visually detectable epoxide residue on theinterior, solvent extractions of the surface and infra red analysesindicated the presence of epoxide. The internal surfaces were smooth andhad a bright appearance.

Example 3 Like operations with billets of aluminum, zinc, magnesium andcopper, and their alloys, can be performed with polyethylene as aresist, e.g., the so-called regular branched type sold under thetrademark Dynk by Union Carbide Plastics Co., or the linear type soldunder the trademark Marlex by Phillips Petroleum Company, or thecommercial polyethylenes of other suppliers. These are obtainable inpellets which are solid at room temperature, rubbery at 300 degrees F.,and melt easily when heated to 360 degrees F. or above. Such are chargedinto the heated billet, and the schedule of rolling from 900 degrees F.was accomplished. Upon opening the hot and cold rolled strip, theinterior was found in good condition.

In the practice of Examples 1 to 3, it was found that very thin channelswere sufficient: and that a large part of the resist could be squeezedout, during the succession of rollings, without the residual film losingability to prevent welding: that is, the thickness of this film was notapparent to the eye, and probably was of the order of a fewten-thousandths of an inch or less. The resist so expelled, during theearly stages of hot-rolling, darkened and charred upon the air exposure,but such charring did not occur internally when the air access wasprevented by the surrounding metal.

Examples of practice in which the resist was charged into a warm billetwhich was then sealed, heated and rolled, are:

Example 4 Billets of aluminum, zinc, magnesium, and copper, and theiralloys, with an end of each sealed, were heated to 350 degrees F., andcharged with pellets of commercial polypropylene (e.g., that availablecommercially under the trademark Profax), which was solid at roomtemperature and became rubbery at 300 degrees F. The pellets melted andthe resist filled the channel without porosity. The open ends werewelded shut without incident. The charged and sealed billets were heatedto 900 degrees F. and rolled. After the schedule of hot and coldrolling, the laminations of the strip can be easily separated, and theinterior surfaces and residual resist were found in good condition,without welds.

Example 5 Billets as in Example 4 were prepared, heated to 360 degreesF., and charged with the polyethylene pellets. The open ends were weldedshut, and the billets heated to 900 degrees F. and rolled. There wasminor leakage at welds, with darkening of the exudate: but the interiorswere in good condition after opening.

6 Example 6 A silicone resin (e.g., that sold under the Dow-Corningtrademark Z-6018) can be used as the resist during a heating and hotrolling schedule. A heat-hardening cyclic tetramer resin was used, ofthe approximate formula where R is a phenyl and R is an isopropyl group.This is effective up to temperatures of 900 degrees F. in billets ofaluminum and its alloys. Upon filling into the channel with the billetat 300 degrees, the hard solid became liquid with some foaming. The endwas welded shut, and the billet heated to 900 degrees F. in itsschedule. When there was leakage by imperfect welding, the exudateshowed polymerization: the internal resin, after cooling, was found tobe a porous hard resin which swelled in acetone but was not totallysoluble and exhibited no damage under infra red examination.

The same silicone resin was loaded into a cold ingot, the ends weldedshut, and the ingot heated to 900 degrees F. and rolled hot and cold to0.016 inch thickness. The laminations separated easily, and the internalappearance was of smooth bright metal. The residue was of microscopicthinnes but had continued in its weld-preventing behavior.

The practices with the resists of Examples 1 to 3 can be performed bycharging the resist into the channel or channels of a cold ingot,sealing as by welding, and then heating to hot rolling temperature andeffecting the schedule of rolling operations: and the resists ofExamples 4 to 6 can be employed by pre-heating the ingot to hotrollingtemperature, quickly charging with the resist and immediately conductingat least the breakdown or conformance passes of hot-rolling. In general,the channel thicknesses of the ingots or billets are determined by thenecessities of making such channels, rather than by the need of having alarge quantity of the resist originally present. Therewith, the channelsmay be open at the ends or become opened by internal liquid pressureduring the rolling, so that half or more of the resist escapes withoutprovoking welding, during the course of the hotrolling. Thus, when abillet has been reduced from 8 inches to 2 inches total thickness, theinternal layer of resist may be of the order of one or two thousandthsof an inch: and this billet can be further reduced to a strip of 0.250inch or less thickness without welding, with most of the resists setout.

In general, it has been found that the behavior of the resist during ahot-rolling schedule of up to 15 minutes can be predicted by noting thebehavior of the resist when heated for a like time in a sealed autoclaveof the metal. Thus, with Example 1, a parallel test by welding thebillet at one end, heating to 300 degrees F., charging essentially fullywith the epoxy resin pellets and permitting foam to subside, sealing theother end by welding, and then heating to 900 degrees F. for an hour,resulted in some leakage apparently by weld imperfection with theefiluent charring, whereas after cooling and opening, the internalprotected resist had not charred and infra red examination did notindicate damage.

Example 7 An aluminum block having an internal channel was filled atroom temperature with a polycarbonate resin,

7 (e.g., that available commercially under the tradename Lexan, of theformula where n represents as usual the number of the stated units inthe polymer. The open end is easily welded shut, and no leakage developsduring the heating to 900 degrees F. After heating, the resist is foundin good condition, as a hard tough resin which is insoluble in acetone,and shows no damage under infra red examination.

An ingot of 3003 aluminum alloy, over 4 inches thick with a core channelabout 0.125 inch thickness, was homogenized 18 hours at 1,100 degrees F.and cooled to room temperature. The scalped thickness was 4 inches. Thechannel had V sections at its edges, /2 inch wide with a 0.005 inch edgeradius. The billet was thoroughly cleaned, and one end welded with aflux coated 1100 welding rod. Polycarbonate pellets were tamped to essentially fill the channel with a packing density of 55 percent. Theopen end was closed by like welding. The billet was then held for anhour in a furnace at 900 degrees F. Leakage through the welds developed:with carbonaceous deposit in the furnace. The hot billet was thensubjected to thirteen hot rolling passes, reducing it from 4 inches to0.15 inch: it was annealed and rolled to 0.090 inch, followed by afurther annealing. It was reduced to 0.024 inch in two passes, againannealed, and rolled to 0.016 inch. Each intermediate annealing was forone hour at 800 degrees F. The rolled strip was completely openable.

Example 8 A linear polyamide resin (e.g., one of those polycaprolactamsknown commercially by the tradenames nylon-6 or Zytel) having thefollowing structure is employed by introducing the pellets into analuminum billet while the latter was heated to 440 degrees F., at whichtemperature the resin is rubbery and can be packed. The closure weldingis efi'ected. When, because of imperfect welding, there was minorleakage, there was charring of the exudate during heating for one hourat 900 degrees F. After the heating at 900 degrees F, the internalresidual resin material is a light straw-colored cheesy solid, insolublein methyl alcohol, and showing no damage under infra red examination.

Example 9 A hollow aluminum billet with the channel closed at one endwas heated to 300 degrees E, and commercial iron stearate introduced andthe channel welded shut. This was a mixture of ferric tristearate and(St) Fe-O-Fe (St) where St denotes -O-CO- (CH2)17H. It was a dry powderat room temperature and liquid at 300 degrees F. When there was leakage,due to imperfect welding, during heating to 900 degrees F., the exudatecharred but the internal material was found not to have changedvisually, being insoluble in acetone, and showing no damage under infrared examination.

Example 10 The procedure of Example 9 was followed, with aluminumstearate, which is a dry powder at room temperature and is rubbery at300 degrees F. The billet was heated to 380 degrees F. for the loading;and the billet channel welded shut before heating to 900 degrees F.Again, when, because of imperfect welding, there was leakage, there wascharring of the exudate. The internal material yellowed but wasotherwise visually unchanged; it was insoluble in acetone and showedminor damage upon infra red examination.

A billet as in Example 7 was first heated at 900 degrees F. for threehours, with one end welded. It was then placed vertically, and thealuminum stearate powder introduced, with melting. The billet was thenimmediately pushed horizontally into the rolls for the first pass,starting with the open end: and the same rolling and annealling scheduleobserved. The welded trailing end burst open at the first pass, and muchliquid resist was discharged. The rolled strip was completely openable.

The tests of Examples 7 to 10, and like tests with the resist materialsand metals of Examples 1 to 6, have been made at temperatures exceeding900 degrees F. for times up to an hour and a half or more, with thestated results. Such materials thus can be employed in the procedures ofExamples 1 to 6, by heating prior to the charging, or by charging at alow temperature and then sealing and heating, and with the performanceof hot-rolling operations at like temperatures of 900 degrees F. orover, all within the time during which the resist material remainselfective. When lower temperatureztime factors are involved, otherorganic materials may be employed.

Example 11 A terephthalic-isophthalic polyester (e.g., that commerciallyavailable under the tradename Videne), which is commercially availablein pellets which become rubbery at 300 degrees F., was employed. It hadthe general formula where R represents the paraor meta-phenyl nucleussingly or in mixture. The hollow aluminum billet was heated to 350degrees F., loaded, and welded closed. Minor leakage of a resinousmaterial occurred during heating for a hour to 900 degrees F. Uponcooling, the internal resin was a yellow wax-like solid which exhibitedthe effects of some depolymerization: it was insoluble in acetone ortoluene, and had suffered no damage, according to infra red examination.It may be noted that infra red examination can reveal change ofintra-molecular structure, but is not a sure guide as to polymerizationor partial depoly-merization.

Example 12 A novolac phenolic resin (e.g., that available under thetradename BR254, Union Carbide) has been employed under the statedheating to 900 degrees F., with aluminum. The resin was apara-phenylphenol-formaldehyde resin of the formula being a hard solidat room temperature, and a liquid at 300 degrees F. The resincommercially available under the trademark BR-254 was used. This wascharged into the cold billet; the billet was welded shut and heated to900 degrees F. After cooling and opening, the resin had a very darkcolor, was partially soluble in acetone, and exhibited no damage effectunder infra red examination.

A billet was filled with the phenolic resin at room temperature to apacking density of percent, as described for Example 7, and rolled withlike annealings. The rolled strip was completely openable.

A like billet was heated at 900 degrees F. for three hours, with one endwelded shut. It was placed with the open end up, and the phenolic resinintroduced to substantial filling; then lowered to horizontal, and alike rolling schedule performed. The welded end burst open during thefirst rolling pass and a large amount of the liquid resist wasdischarged. The rolled strip was completely openable.

Example 13 A polymethyl styrene resin was used, of the general formulaCI-I Z 1 This is commercially available as pellets under the trademarkCynac-400 from the American Cyanamid Company; and is rubbery at 300degrees F. The billet was heated to 340 degrees F., loaded, and the endswelded shut. Upon heating to 900 degrees F., there was leakage of aresinous material. Upon cooling, the internal resin was anamber-colored, fused, hard, britle resin; soluble in toluene, butshowing no damage under infra red examination.

Polystyrene resin was packed to 50 percent density into a billet at roomtemperature, as set out for Example 7: the billet was then weldedclosed, and subjected to the heating and rolling schedule as in Example7. The rolled strip was completely openable.

The materials of Examples 11 to 14 can be employed as in Examples 1 to6.

Example 15 A magnesium billet had its internal channel filled withepoxide resin, as in Example 2, and sealed. It was heated to 700 degreesF. and hot rolled. The internal surfaces were smooth and bright.

The surface effect prodncted by the use of resists which are liquidduring at least the early part of the hot rolling may be illustrated by:

Example 1 6 An aluminum billet 2 inches thick, with a 0.100 inch thickchannel, received a polyethylene strip about 0.005 inch thick andslightly narrower than the channel width, at room temperature. It waswelded shut and heated to 600 degrees F., and warm-rolled to 0.016 inchin the range 600 to 300 degrees F. During the early passes, the liquidresist broke the weld at the trailing end of the billet and a part ofthe resist was squeezed out. Upon opening, the internal surface wasexceptionally bright, indicating that the material was liquid or highlyplastic during the rolling. Both internal surfaces had resist materialadherent thereto, as shown by the lesser action of caustic solutionsthan at exterior surfaces or filecleaned surfaces.

The protective effect of the metal during the hot stage is brought outby the instances where leakage past a Weld occurred; noting that theexudate darkened and decomposed under like temperature condition whereasthe encapsulated resist exhibited its desired properties.

Practice with the foregoing materials is shown in the drawings. InFIGURE 1, the ingot B has internal longitudinal channels 11,illustratively located in the median plane M between the billet surfaceswhich are to be rolled. The organic resist materials act. by preventinginterpenetration of the metal laminate material through the resist filmand welding is prevented, and the film is continuous. It is notnecessary to provide originally a thick resist layer as with the use ofrefractory powder resist where the resist residue must be severalgranules thick at the end of cold rolling; and hence a channel 11 may beinch thick or less, even with a 12 inch ingot which is to be rolled to afinal thickness of 0.016 inch, or an extension of 700 times.

It has been found preferable, with resists which are liquid during theearly or breakdown stages of the hotrolling, to have the channels 11with edges of chisel-shape, as shown in FIGURE 1, with the upper andlower surfaces of each channel formed by parallel planes, and with theedges of each channel formed by convergently tapered surfaces which havean angle of 10 to degrees relative to one another. Practices with anglesof 14 and 28 degrees show that there is little difference between themfor the liquefied resists above. The tapered surfaces can be planeswhich merge by minor curvatures with the aforesaid parallel surfaces,and which are joined by a curve of small radius: e.g., with channels A;inch thick, the edge curvature can be around inch in radius. During theinitial rolling, the liquid resist coats the internal surfaces: and asthe metal is forced together at the channels, the tapered edges providesmooth transitions so that internal roughness does not develop.

Channels of other cross-sections can be employed in accordance with theinvention. In FIGURE 2, the channels 11a are oblong, with roundedcontours at the edges. In the initial hot-rolling, the upper and lowersurfaces of such channels move toward one another, and the resistmaintains its coating upon the internal surfaces; ultimately providing afilm of essentially uniform thickness.

In FIGURE 3, the channels at the end 12 of the ingot are shown as closedby peening and a welded seam 13, it being understood that this closureextends across and closes the entire end in the complete ingot. With thesealed end down, FIGURE 4, the resist material may be introduced as aslab, sheet, or powder, e.g., through a guide or hopper 14. When theresist makes contact with the hot channel walls, FIGURE 4, as it movesdownward, it melts thereagainst to provide a coating: when a strip Ainch thick and 2 or 3 inches wide is thus fed, lateral movements duringfeeding and While within the channel assure the coating: like spreadingoccurs with powder particles. This coating effect is assisted by foamingand bubbling of the resist, FIGURE 4; in practice, by the completion ofthe feeding, fumes are billowing out, displacing the air from thechannel. If the ingot has been previously heated, as stated above, theresist melts, discharges its air of porosity and its volatiles, if any,and the upper end 15 can now be peened and welded shut so that theresist material is totally enclosed against entry of gases from theatmosphere and against escape of any resist material. Alternatively, thebillet can be quickly brought to horizontal position, without sealingits open end, and pushed into the rolls. If the ingot is cold, theresist can be introduced, with tamping and vibration to assure a tightfilling, and then peened and welded shut.

The loaded and closed billet B is then subjected to its schedule ofheating and rolling. With aluminum and its alloys, this is usually aheating 30, FIGURE 5, to 900 degrees F., with a succession ofhot-rolling passes 31 to reduce the material to about four to eighttimes the desired final thickness. The hot-rolled strip is then annealedin step 32 at 900 degrees F. for 30 minutes, cooled, and subjected to asuccession 33 of cold-rolling passes to bring it to final thickness as astrip S. More than one intermediate annealing can be employed, as setout above.

When the rolling can be conducted immediately upon loading the billetchannel with organic resist, as in Examples 1, 2 and 3 above, the billetmay be brought to the desired condition and temperature for hot-workingbefore the resist is introduced. For example, an aluminum alloy ingot B,FIGURE 6, can be heated to 900 to 1,000 degrees F., and a resist inliquid form can then be inserted into the channel at the end which isinitially to be fed into the reduction rolls 16. This can be done by aninjecting pump cylinder 17 having a nozzle 18 which enters a channel ordiscontinuity 19 of the billet B, and deposits a quantity of the resistwithin the channel at the leading end, as shown by the dotted lines 20,continuing the deposit until the nozzle is fully withdrawn. When thebillet has several channels, it is preferred to charge all channels atthe same time, so that air-exposure of heated resist is kept to aminimum time. The billet B is immediately introduced to the rolls I6 anda reduction made which closes the walls of the channels 19 upon theresist so that air access thereto is thereafter prevented, and theresist is spread and distributed between the internal wall surfaces,being pushed along the channel during the rolling and the excesssqueezed out as the rolling pass is ended. Therewith, the resistprovides a thin film which prevents welding of such internal surfaces.Silicone greases or oils having the polysiloxane structure of a chain ofsilicon and oxygen atoms, with the silicon atoms having hydrocarbongroups connected thereto, for example of the formula Len. (H,

(e.g., the commercial material sold under the tradename DC*710) can beso employed, with the pump delivering the resist at a room temperatureof 70 degrees F., 'or a temperature of below 500 degrees F., e.g., 300to 400 degrees F., at which there is essentially no degradation upon aircontact during the time for injecting and the early rolling. The resistis immediately heated from the hot billet, upon injection, but then itis protected against major contact with oxidizing substances such asair. Minor degradation can occur between the surface of the mass and theair present in the channel, but in practice, this has not been foundharmful when the rolling is started quickly. There appears to be a timefunction for the degradation, so that when the hot-rolling attemperatures above, say, 600 degrees F. is completed within fiveminutes, the silicone continues effective for the hot rolling, andduring a subsequent cold rolling. has been cold-rolled to final gauge,and is heated for 30 minutes or more for annealing, the siliconedecomposes, with the production of negligible amounts of gas and silicaper unit area of the laminate stock, and no notable bulging of thelaminations away from one another.

This pro-heating of the billet to hot-rolling temperature, and theimmediate hot-rolling, can be employed with the several resists andmetals described above. It is applicable with other organic compoundresists having the stated characteristics and even with resists whichundergo polymerization at hot-rolling temperature, provided that thehot-holling is completed before polymerization has progressed to a stageat which the anti-welding effect is not maintained during the course ofthe rolling schedule. For example, if the compound requires two minutesor more for the polymerization to a condition in which the product is nolonger thermoplastic or extensible under rolling pressure, it can beused in a schedule of hot rolling and cooling to a temperature at whichthe progress of polymerization is slow; because it is feasible inpractice to conduct the hot-rolling of selected billet sizes and thecooling within two minutes, with the resist then present in a formproper for cold rolling.

In practice, in making tubular bodies of 12 inches diameter or less, itis economical to form the original bil- When such a strip h let withmore than one channel 11, or 11 as shown in FIGURES l and 2: but it willbe understood that the invention can be employed with billets having asingle channel and that, for some employments such as the making of heatexchange bodies, the internal channels may be connected within thebillet body. Therewith the billets need not be original hollow ingots,but can be prepared by other procedures known in the art of makinglaminate stock, with care taken to assure the closure of each channel orgroup of channels against atmosphere penetration or the escape of resistmaterial into places where it can interfere with the regular course ofreduction of the billet. Thus the channels may be provided by castingmolten metal about cores which are later removed, by casting moltenmetal about hollow tubes which become integrated with ingot metal, or byboring or piercing.

The strip S (FIGURE 7) has a number of longitudinal internal resistresidues 35 equal to the number of channe s 11 or 11a in the originalbillet; and these residues may be present in such thin layers that theyare each represented by a single line in the drawing. These residues 35separate the metal lalninations 36, 3'7, with the laminations connectedat the lateral edges of the resist residues by the longitudinal metalportions 38. When more than one channel and residue is present, thestrip S can be called multi-wide because it can be parted into a numberof single-wide strips by severance, as represented by the line 39, alongupright surfaces which extend along the metal connections 38 betweenadjacent residues 35 so that each strip retains a part of suchconnection. The edges of the strip S may likewise be severed at surfacesrepresented by the line 40, so that each single-Wide strip has edgeconnections of essentially the same lateral dimensions from thecorresponding edges of the resist residue. Decoration, such as theprinting of pictures and Words can be done, before or after severanceinto blanks, and the laminate stock can be embossed with ribs andgrooves for stiffening the walls after opening: wherewith the resistresidue continues to act to prevent internal sticking or welding. Thestrip S can likewise be severed transversely to provide container bodyblanks, which are opened or expanded as shown in FIGURE 8, wherewith thelaminations 36, 37 provide the major portions of the tubular bodies T;and therewith the wall thicknesses of the bodies are determined by thefinal rolled gauge of the strip, being illustratively half this gaugebecause the resist layer 35 can be of insignificant thickness. The partsof the integral connections 28 for the specific body T are present asexternally projecting fins 4,1 which may be trimmed and conformed to thegeneral body cross-section, FIGURE 9.

When the resist material is selected from the substances described inthe examples, the residue is adherent to the internal walls of the bodyT, and is compatible with organic enamels and lacquers. Thus, after thefins 41 have been conformed as shown in FIGURE 9, wherewith thereentrant angles 42 have been essentially removed at the interior, anenamel may be applied as by the conventionalized spray nozzle 45 duringpassage of the body along the same. The enamel can then be dried andbaked.

Illustrative organic enamels or lacquers have solid components ofoleo-resins, phenolic resins, epoxide resins, or vinyl resins along withpigments and fillers; and include resin solvents such as hydrocarbons,ketones and esters. Solvents which dissolve the resist residues merelyform a modified organic coating, assuming the resist resin residue andthe added resin are compatible. When the solvents do not act upon theresist residues, and are eliminated during drying, a fluxing together ofthe resist residues and the enamel resins can occur during baking.

Organic resists which have been found effective for the procedure havethe common chemical and physical attributes that they have a molecularweight above 500; exhibit thermoplasticity, i.e., being liquid, uponheating under non-oxidizing conditions in the range of 500 to 1,000

13 degrees F. so that they respond during the extension of the metalarea and are deformed uniformly therewith; and do not change bydegradation or polymerization during such heating and pressure in theabsence of air so that such response is not exhibited. Thermoplasticityherein has the usual meaning of capability of being deformable withoutrupture or significant decomposition when heated above room temperature.It has been found that the materials can be tested as to behavior duringrolling, by filling a tube, made of the metal which is to form thelaminate stock, substantially full with the material, sealing the endsas by welding, and heating to the proposed operating temperature, e.g.,900 degrees F. for one graph essentially the same as the untestedmaterial.

The properties of the useful organic resist materials include theability to endure the temperatures of heating, with exclusion of oxygen,e.g., air, without loss of antiwelding properties, so that they continueeffective for that purpose through the course of reduction,illustratively by a schedule of hot and cold rolling preferably with amaintained adhesion to the metal surface which is greater than theinternal cohesion within the resist layer, and the ability to accept andestablish adhesion to organic enamels later applied thereto. When theproduced strip material is to be in contact with foodstuffs, e.g., whenthe tubular body T of FIGURE 6 is to be part of a food container, theresist material should not com-prise a toxic component or have a toxicor flavor-change effect. The resist material should extend regularly andin proportion to the extension of length and reduction of thickness ofthe billet metal, so that smooth internal surfaces areproduced: that is,it should be extensible. These properties are presented by the materialsof the examples; the internal surfaces of Example 9 with aluminum metaland silicone resist exhibited excellent dry adhesion for organicenamels, but when subjected to the standard spinach-oxygen test andstored for four days, there Was some loss of enamel adhes1on.

The continuity of the residual resist films on the internal wallsurfaces on laminate stock prepared from an aluminum alloy (commerciallyknown as 6061) was tested by treating a standard area with air-freecitrate buffer solution of pH 3.5 at 100 degrees F. Comparable barealuminum alloy surfaces are thereby attacked, and hydrogen gas isevolved at a rate of 0.100 to 0.120 milliliter (measured at standardtemperature and pressure) per square inch per day. With polyethyleneresist as in Example 4, 2-6018 silicone resist as in Example 9, and Epon1007 resist as in Example 1, the hydrogen evolution Was 0.052 to 0.059milliliter per square inch per day, showing that the extremely thinresidual material was present as a protective agent.

In general, the satisfactory resist or anti-welding materials may bedefined chemically as organic compounds (the term as usual including thesilicone compounds having hydrocarbon groups in the molecular structure)which are waxy, rubbery, or resinous in behavior at room or slightlyelevated temperatures, which endure exposure to temperatures around 900degrees F. in the absence of oxygen, and which have a molecular weightabove 500.

Among the useful organic compounds so defined are:

(a) Resinous polymers of (CH -CR) structure, where R can be hydrogen,alkyl hydrocarbon groups of 1 to 4 carbon atoms, phenyl,alkyl-substituted phenyl, and polyalkyl-substituted phenyl, and ndenotes the presence of a plurality of such units in chain (inclusive ofthe resins known as polyethylene, polypropylene, polystyrene,polymethylstyrene, polyvinyl-toluene, polybutene, copolymer)s ofpolybutene with polyethylene and/ or polypropylene (b) Metal soaps ofthe structure (R 'CH -CO -R where R is an aliphatic or olefinichydrocarbon group of 10 to 16 carbon atoms, R is a metal ion, and pdenotes a number of acid groups no greater than. the replacement valencyof the metal whose ion is being used (inclusive of sodium and othermonovalent metals, calcium and other bivalent metals, aluminum and ironand other trivalent metals, and of the stearates and oleates):

(c) Essentially linear condensation polymers of the structure =(R -CO-R-CO),,=; where R represents a normal hydrocarbon group of 2 to 10 carbonatoms, isopropylidene-bis-(para, para prime-phenoxy),

:(normal C H -NH)=, O-R -O- and --NH-R -NH; R represents a normal alkylhydrocarbon group of 2 to 10 carbon atoms, meta-phenylene,para-phenylene,

=(normal C H -NH)= and isopropylidene-bis-para, para prime-phenoxy; Rrepresents a normal alkyl group of 2 to 10 carbon atoms; and q denotesthe presence of multiple units in chain (inclusive of polycarbonates,polyamides such as the linear carboxylic acidzamine condensationsincluding dibasic acid:diamine polymers and caprolactam polymers, andpolyesters, e.g., of terephthalic, isophthalic, adipic and sebacic acidswith ethylene glycol, propylene glycol and homologous glycols):

(d) Thermoplastic resins having multiple phenyl nuclei in chain, to wit:phenol-aldehyde or phenolic resins (inclusive of the novolacs such aspara-phenyl-phenol:formaldehyde condensate resin), and epoxy resins withmultiple phenyl nuclei (inclusive of the bis-phenol epichlorohydrincondensates):

(e) Polyorganosiloxanes or so-called silicones having alternate siliconand oxygen atoms in chain with the free valencies of the silicon atomsjoined to hydrogen or hydrocarbon groups directly or through oxygen(inclusive of the linear silicone polymers and of the compounds withring structure or cyclic tetramer units as in Example 6 above, and ofthermoplastic compounds having molecular cross-linkages through oxygenatoms between silicon atoms of two or more chains):

(f) Polyterpene resins.

The heating and presence in enclosed channels, during the process,prevents entry of oxygen from the air. General decomposition reactionsof organic compounds can cause gaseous products, and the pressurethereof causes a shifting of the equilibrium point so that the reactionceases when the sealing prevents escape. In practice, it has been foundthat the decomposition or depolymerizations occurring, which do notyield gaseous products, are apparently without destructive effect uponthe selected resist materials, noting the results of practice and infrared examination as stated above. Polymerization of originally highmolecular weight materials also is not deleterious, provided that aninfusible, highly brittle product does not result so that theantiwelding capability is lost during completion of the reductionoperations.

The procedure comprises the exclusion of oxygen while the billet is atelevated temperature. This is preferably done by sealing the channelagainst entry of air: but under the invention the exclusion may beeffected in other ways. For example, after first heatings and rollings,the ends may be clipped and the rolling continued. It has been foundthat with a silicone resist material in an aluminum billet, the endscould be peened without welding, so that part of the resist was extrudedin the first rolling pass: the laminate stock after rolling to gauge wasfound to open easily and had a good internal appearance.

Another practice of the use of high molecular weight organic resists isthat of conforming the billet to the resist or anti-welding materialbefore heating to the temperature required for hot-rolling the billetmetal. Thus, a billet having its channel partly filled with the resistmay be initially rolled at a temperature below that at which the resistis degraded upon air contact; whereby to distribute the resist, expelair, and conform the billet to the resist without air-filled pockets orspaces. Such a temperature can be a cold rolling condition for themetal, and one at which the resist extends easily under roll pressureeffects upon and in the billet and is for example a stable fluid. Thedegree of reduction can be small during this initial conformancerolling, e.g., with a billet 8 to 14 inches thick and the longitudinalchannel inch thick, the over-all reduction of thickness may be less than5 percent, and essentially no cracking develops. No internal pressureneed develop, as the end or ends may be left open for escape of air andexcess resist.

A billet having one or more channels, closed at the lower end as inFIGURE 4, receives the resist material at room temperature or at betweenroom temperature and about 500 degrees F., at which the resist isliquefied but not damaged by heating in contact with air. A suitabletemperature for the described organic compound resists is 300 to 400degrees F. It is difficult and often expensive to prepare billets with achannel less than around A; to inch in thickness; noting that a greateroriginal thickness of resist is not required to maintain the anti-Welding action, since upon reduction of such channel to microscopicthinness, e.g., one ten-thousandth of an inch or less, the welding isstill prevented. Hence, the channel cavity can be filled part full ofliquid resist or partly filled with a strip of resist material muchthinner than the channel. The billet is then rolled at a temperature,room or above, at which the resist is not damaged by air contact, bylight passes until the resist is spread evenly over the channelsurfaces, and therewith the billet has its channel thickness reduced toconform to the resist present and thus the residual channel space isfull, with expulsion of air and some of the resist material. The billetis then heated to the temperature at which the hot-rolling of the metalis to be started, e.g., 900 to 1,000 degrees F. for aluminum and itsalloys, and the schedule of hot-rolling performed.

In practice, an advantage of the very thin resist residues is thatintermediate annealing or reheating can be conducted during the couse ofthe hot-rolling without causing bulging or expansion, which may occur ifa large thickness of resist having a gaseous product or an appreciablevapor tension at the heating temperature, is present. The billet and theresist afford mutual protection to each other: the billet encloses andprotects the resist from decomposition or vapor formation, and theresist prevents oxidation of surfaces of the billet channel or channels.The final laminate stock has bright and clean internal surfaces. Withthese practices of lightly rolling the billet to reduce the channeldimension before heating to rolling temperature, it is preferred to havethe channels 49 of rounded-end section, as in FIGURE 1, or of ellipticalcross-section, as shown in FIGURE 2, because therewith, the residualcavity after rolling has a more uniform thickness without excessthickness at the lateral edges of the reduced channels, such as may bepresent after a light schedule of early rolling with channels ofrectangular section.

When a silicone grease or oil (such as that commercially known by thetradename DC-710) is used, it can be employed at 70 degrees F., and theconformance rolling done at this temperature. With polyethylene, atemperature of 300 degrees F. can be employed. Suitable temperatures forother compositions are indicated in the examples.

In forms of practice in which the resist is brought into a billetalready heated to hot-rolling temperature or in which the billet isheated to such temperature with the resist therein, and then forthwithsubjected to hot-rolling, the developing of gas by degradation of a partof the resist it frequently of assistance in providing a plenum effect,so that the entry of air is prevented. Such gas evolution is greatest atthe start of a rolling schedule: and drops as the metal cools during andbetween rolling passes. In addition, the extension of the length of thechannel and its reduction of thickness hinder and prevent the travel ofany evolved gas along the channel.

The procedure is effective with metals which can be rolled attemperatures of 1,100 degrees F. or below: inclusive of aluminum, zinc,copper, magnesium and other non-ferrous metals and their alloys: and isparticularly of value with such materials which require hot-rolling orheat-treating temperatures of 500 to 1,100 degrees F.

In accordance with this procedure, the resist is preferably a liquidduring initial rolling passes so that it conforms to the channel; andexhibits increased viscosity during later rolling passes at temperaturesbelow 500 degrees F. and down to room temperature.

The procedure includes the employment of original resist channels ofsuch original thickness that insignificant thicknesses of resistresidues are present in the final step, e.g., below 0.001 or 0.0005 ofan inch. This is particularly valuable when the adhesion of the resistresidue to the metal is greater than the internal cohesion of the resistso that, upon opening or expansion, the inner surfaces of both metallaminations have films of the resist residue thereon, with theseparation usually making the films of essentially the same and likethickness throughout. For this, it is preferred to execute the rollingwith reversal of the billet at successive passes: that is, the trailingend at one pass is made the entering end at the next pass, so that anyeffect of longitudinal movement of the resist, independently of themetal extension and with an effect of increasing the relative resistthickness at the trailing end compared to the entering end, iscompensated by the reverse rolling. Therewith, the fluid ity of theresist expelled at the trailing end of the billet is not as destructive,e.g., by abrasion, as a resist of solid refractory particles would bewhen the trailing end is immediately fed to the rolls for the second orreverse pass.

It has been brought out above that the necessary residual thickness ofresist material, in the final strip, can be very small, thatcorrespondingly a very thin channel can be effective in a thick ingot,that technical considerations restrict the minimum channel thicknesseswhich can be provided in ingots, and that in fact the quantity oforiginal resist material can be less than that for filling the channel,as shown by the expulsion of a large part of the originally introducedresist at the end of the first and subsequent hot-rolling passes. Theaction during the first hot pass is, on the one hand, to conform theingot to the resist so that air is expelled and its re-entry prevented;and on the other hand to spread the resist so that it fills the reducedchannel with coverage at all surfaces thereof. In practice, where bothends of a channel were closed by Welding, the movement of liquid resistalong the channel incidental to the rolling causes such a high pressureto develop that the closure at the trailing end of the ingot bursts openand excess resist is expelled. Comparably, with FIGURE 6, for example,where the trailing end can be open, a like expulsion occurs.

In some cases, where the hot rolling temperature makes the resist a thinliquid and there is rapid rolling of a billet which is open at thetrailing end, the resist may be caused to travel along the channel athigh velocity and without the amount of lateral spreading required tocoat the entire internal surfaces. This is revealed during the hotrolling by proper coating of the inner surfaces for the first half ofthe billet, for example, and by the lack of full coating at the channeledges for the second half of the billet; so that local pressure weldsoccur at the channel edges, with decrease of the width of the resistresidue at such pressure-Welded regions in the final strip whereby partsof the strip must be discarded if accuracy of width is demanded.

It has been found that in such cases coating of the internal surfacescan be improved by a roughening of the 17 internal surfaces. Suchroughening need not be and preferably is not of major extent. Forexample, after an ingot has been cast with one or more internalchannels, of say 0.120 inch thickness, and these are broached orburnished, a roughening not perceptible by touch will produce aretardation of the longitudinal flow of the liquid resist, duringrolling, with development of a back pressure effect which causes lateralspreading and coating. Such a roughening can be produced by etching: forexample, with aluminum and aluminum alloys, a treatment with hot causticalkali solution for a few minutes, following by rinsing produces amicroscopically rough surface, of the order of to 50 micro inchesbetween hills and valleys. This etching and rinsing is preferably donebefore the ends are closed. Upon introduction of the resist either Withsealing of the ends as in FIGURES 3 and 4 or without such sealing as inFIGURE 6, the roughened surfaces act to detain the resist at the metal:resist boundaries of the channels during the courses of the rollingpasses. Upon hot rolling, the longitudinal extension of the billet tostrip form gives internal surfaces, after opening, which have a somewhatmatte appearance but without significant depths of the surfaceirregularities.

In cases where a great reduction of thickness is scheduled, particularlyin cold rolling passes, and the residual film of resist may become toothin or discontinuity may develop therein, the invention permits thereplenishment of resist. For example, the leading end of the strip canbe opened, more liquid resist of the same or a dilferent typeintroduced, and the rolling continued, wherewith the added resist massis caused to travel along the channel during the rolling andre-establish a desired film thickness for successive rolling passes. Itis notable that this cannot be accomplished with resists which aregranular, refractory solids, and do not have the flow properties forsuch replenishment.

The invention is not limited to the illustrative forms, and may bepracticed in many ways within the scope of the appended claims.

What is claimed is:

1. The method of producing a laminate metal stock which comprisespreparing a billet of a metal selected from the group consisting ofaluminum, zinc, copper, magnesium and their alloys, and said metalrequiring a hot-rolling temperature of 500 to 1100 degrees F., saidbillet having an internal cavity, introducing into the cavity an organiccompound having a molecular weight above 500 and which at thetemperature for hot rolling of the metal is a liquid and is extensibleat cold rolling temperatures for the metal and heating the said organiccompound to lower the viscosity of the same to a condi tion for easyspreading, reducing the billet at a temperature between 500 and 1,100degrees F. for closing the cavity surfaces upon the said organiccompound and thereby expelling gases from the cavity, and spreading thesaid organic compound and therewith coating the cavity surfaces with thesaid organic compound, and continuing the reduction with air excludedfrom the cavity in the metal undergoing reduction, said heating andreduction including at least one step of bringing the billet to atemperature of 600 to 1,100 degrees F. with the said organic compoundcontacting the billet cavity walls at such temperature.

2. The method as in claim 1, in which the said organic compound is aresin having units of the structure CH CHRl where R is selected from theclass consisting of hydrogen, alkyl groups of 1 to 4 carbon atoms,phenyl, alkyl substituted phenyl and polyalkyl substituted phenyl, and ndenotes the presence of a plurality of the units in chain.

3. The method as in claim 2, in which the said organic compound ispolyethylene.

4. The method as in claim 1, in which said organic compound is a metalsoap of the structure (R CH CO R where R is selected from the classconsisting of aliphatic and olefinic hydrocarbon groups of 10 to 16carbon atoms, R is a metal ion, and p is a number not greater than thereplacement valency of the metal whose ion is selected.

5. The method as in claim 4, in which the organic compound is ironstearate.

6. The method as in claim 1, in which the said organic compound is anessentially linear condensation polymer having units of the structurer..r...u

where R is selected from the class consisting of normal alkylhydrocarbon groups of 2 to 10 carbon atoms, isopropylidene-bis- (para,para-phenoxy) :(normal C H -NH): O-R -O, NH-R -NH--; R is selected fromthe class consisting of normal alkyl groups of 2 to 10 carbon atoms,meta-phenylene, paraphenylene,

:(normal C -H -NH)= and isopropylidene-bis-(para, para' phenoxy); whereR is a normal alkyl group of 2 to 10 carbon atoms; and q denotes thepresence of multiple units in chain.

7. The method as in claim 6, in which the said organic compound is apolycarbonate resin.

8. The method as in claim 1, in which the said organic compound is acondensation polymer selected from the class consisting of thermoplasticresins derived from the reaction of phenols with aldehydes, and epoxyresins with multiple phenolic nuclei.

9. The method as in claim 8, in which the said organic compound is abis-phenol epoxy resin.

10. The method as in claim 1, in which the said organic compound is apolyorganosiloxane.

11. The method as in claim 10, in which the said organic compound is apolysiloxane having units of the structure O----S i--O 0H a Where R isphenyl, R is an isopropyl group, and t de notes the presence of multipleunits in chain.

12. The method as in claim 1, in which the metal is aluminum and thehot-rolling is conducted from a temperature of 700 to 1,100 degrees F.

13. The method as in claim 1,' in which the metal is a copper basealloy, and the said organic compound is introduced while the billet isat a temperature of about 950 degrees F. and the billet is hot-reducedfrom such temperature.

14. The method as in claim 1, in which the hot-reduction is atsuccessively lower temperatures, and a final cold-reduction is employedto attain the desired final dimensions.

15. The method of producing a laminate metal stock which comprisespreparing a billet of a metal selected from the group consisting ofaluminum, zinc, copper, magnesium and their alloys, and said metalrequiring a hot-rolling temperature of 500 to 1,100 degrees B, saidbillet having a longitudinal internal channel with an open end,introducing through said end and into the channel an organic compoundwhich at a temperature for hot-rolling of the metal is a liquid andsubject to decomposition in air and is extensible at cold-rollingtemperatures for the metal, thereafter rolling the billet while at atemperature of 500 to 1,100 degrees F. for closing the channel surfacesupon thesaid organic compound and thereby expelling gases and a quantityof said organic compound from the channel, and continuing the rollingwhile the metal is at a hot-rolling temperature and with air excludedfrom contact with the organic compound by the metal undergoingreduction.

16. The method as in claim 15, in which the surfaces of the internalchannel are first smoothed and thereafter 'etched before theintroduction of the organic compound.

17. The method as in claim 15, in which the said organic compound isintroduced into the channel while the billet is below the temperature ofdecomposition of said organic compound while in contact with the air,and in which the said open end is closed before the billet is heated tohot-rolling temperature.

18. The method as in claim 17, in which the said organic compound is aliquid at a temperature below 500 degrees F., and the billet is warmedto a temperature below 500 degrees F. for liquefaction of the saidorganic compound before the same is introduced.

19. The method as in claim 17, in which the said open end is closedbefore the billet is rolled for reducing the channel surfaces upon thesaid organic compound.

20. The method as in claim 15, in which the billet is heated tohot-rolling temperature before the said organic compound is introduced,and is immediately subjected to .rolling for closing the channelsurfaces upon the said organic compound and expelling air.

' 21. The method as in claim 15, in which the billet is subjected to asuccession of hot-rolling passes and the direction of billet entrybetween the rolls is reversed for successive passes.

22. The method of making laminate strip stock, which comprisesintroducing into a longitudinal internal channel of a billet of metalwhich requires a temperature of 600 to 1,100 degrees F. for hot-rollingan organic compound which at the hot-rolling temperature for the metalis subject to decomposition in air and is a liquid at a temperatureabove room temperature and below 500 degrees F. and is extensible atcold-rolling temperatures for the metal, and hot-rolling the billet bysuccessive passes from a temperature of 900 to 1,100 degrees F. andthereafter cold-rolling the hot-rolled strip.

23. The method as in claim 22, in which the billet is heated tohot-rolling temperature before the introduction of the organic compound,is immediately subjected to the hot-rolling, and reduced to atemperature below 500 degrees F. within five minutes after theintroduction of the organic compound.

24. The method as in claim 23, in which the channel is open at one end,and the organic compound is introduced for a limited zone adjacent saidopen end, and the billet is immediately brought to hot-rolling with theopen end presented to the rolls.

25. The method of producing a hollow metal body having an internalcoating of a selected organic enamel composition, which comprisesintroducing into an internal cavity of a billet of metal selected fromthe group consisting of aluminum, zinc, copper, magnesium and theiralloys, and said metal requiring a hot-rolling temperature of 500 to1,100 degrees R, an organic compound which is a liquid and subject todecomposition in air at a temperature for hot-rolling of the metal andis extensible at cold-rolling temperatures for the metal and iscompatible with the selected enamel, heating the said organic compoundto melt the same within the cavity, hot-reducing the billet at atemperature of 600 to 1,100 degrees F. for bringing the cavity surfacesinto conformity with the liquefied organic compound and for producingthe desired shape with the surfaces of the cavity separated by theorganic compound and with the organic compound protected from the air bythe meta-l of the billet, then cold rolling the hotreduced productthereafter moving cavity surfaces apart to provide the internal hollowof the body, and applying the organic enamel composition to theresist-coated internal surfaces.

26. The method of producing a hollow tubular metal body, which comprisesintroducing into a longitudinal internal channel of a billet of metalwhich requires a temperature of 600 to 1,100 degrees F. for hot-rollinga thermoplastic organic compound which at the hot-rolling temperaturefor the metal is a liquid and subject to decomposition in air and isextensible at cold-rolling temperatures for the metal, heating the saidorganic compound to melt the same within the channel, hot-rolling thebillet at a temperature of 600 to 1,100 degrees F. for bringing thechannel surfaces into conformity with the liquefied organic compound andexpelling a part of the organic compound from the channel and effectingcontact of the organic compound with the surfaces of the channelthroughout its length, continuing the hot-rolling and thereupon aftercooling effecting cold-rolling for producing a laminate strip havinglaminations separated by the residue of the organic composition andconnected at their edges by integral metal from the billet, and movingthe laminations apart for forming the tubular body.

27. An article of manufacture comprising a cold and hot-rollinglaminated metal strip having at least one longitudinal internal channelcontaining a continuous microscopic film of less than 0.001 of an inchthick; said film consisting of an organic resist compound capable ofdecomposing in air at temperatures above 600 F. and having beensubjected to the hot-rolling temperatures of about 9001,l00 F. in theabsence of air; and laminations being integrally connected by metal;along the longitudinal edges.

28. The article of claim 27 further characterized as a hollow metal bodyformed from the laminated metal strip; said hollow metal body havingintegral walls, the inner surfaces of which contain an enamel-coatingcomposition which is compatible with said film of the organicresistcompound.

References Cited by the Examiner UNITED STATES PATENTS 7 2,986,810 6/61Brick.

2,990,608 7/61 Manning l29-470.9 X 3,029,155 4/62 Maier 29-423 X FOREIGNPATENTS 227,369 8/59 Australia. 774,008 5/57 Great Britain. 814,979 6/59Great Britain.

WHITMORE A. WILTZ, Primary Examiner. HYLAND BIZOT, Examiner.

27. AN ARTICLE OF MANUFACTURE COMPRISING A COLD AND HOT-ROLLINGLAMINATED METAL STRIP HAVING AT LEAST ONE LONGITUDINAL INTERNAL CHANNELCONTAINING A CONTINUOUS MICROSCOPIC FILM OF LESS THAN 0.001 OF AN INCHTHICK; SAID FILM CONSISTING OF AN ORGANIC RESIST COMPOUND CAPABLE OFDECOMPOSING IN AIR AT TEMPERATURES ABOVE 600*F. AND HAVING BEENSUBJECTED TO THE HOT-ROLLING TEMPERATURES OF ABOUT 900-1,100*F. IN THEABSENCE OF AIR; AND LAMINATIONS BEING INTEGRALLY CONNECTED BY METALALONG THE LONGITUDINAL EDGES.